Organic cyanine base



Patented Jan. 29, 1946 UNITED STATES U 1 ORGANIC CYANINE. BASE Leslie G.-

-Brooker and Robert H. 'Sprague, Rochester, .N. 1., assignors to Eastman Kodak Company, Rochester, N. Y.,' e. corporation of :New Jersey NoDrawing. ,Application April 18,, 1941, {Serial No. 389,224

13 Claims- This invention relates .to organicbases'and more particularly to what can he called cyaninelbases, dialkylaminostyryl bases and dialkylaminophenylbutadienyl zbases.

cyanine bases, .dialkylamino sty-ry1 bases and dialkylaminophenylbutadienyl bases "have been prepared by removing the elements of'alkyl salt (1. e., by dequaternarizing) cyanine dyes, dialkylaminostyryl dies and dialkylaminophenylbutadienyl dyes. This has been accomplished, for instance, by heating the dyes in a tertiary amine, such as diethylaniline. However, this method is of limited utility since many of the bases which contain longer polymethine chains cannot be prepared by such a process.

Cyanine bases have also been prepared by condensing lepidine or quinaldine with cyclammoni- ;um quaternary salts containing, in a reactive position, a thioether or -a p-acylarylaminovinyl group. This methodis of no utility for thepreparation of diand tricarbocyanine bases,*and in any event, is useful-only for producing bases containing quinoline nuclei.

We have now found that a new-kind oi cyanine bases, dialkylaminostyryl basesand dialkylaminophenylbutadienyl :bases can be prepared by condensing heterocyclic nitrogen bases containing in the alpha or gamma position, i. e., in one of the so-called reactive positions, .a cyanomethyl group, with cyclammonium quaternary salts containing in a reactive position a group, such as halogen, thioether, p-arylaminovinyl, w -arylamino-l,.3-butadienyl or pearyla-mino-l;3;5hexatrienyl. By our :new method we can obtain readily cyanine bases containing long polymethine chains. Our new bases always contain a .cyano group attached to one DI the zmethine groups connecting the two cyclic nuclei, and are frequently much stronger sensitizers of photographic emulsions than the corresponding bases which are devoid oI-cyano groups. We have also found that bases devoid of cyano groups can be prepared from our new bases which contain a cyano group. Thus, we have provided many bases which were heretofore unavailable.

It is accordingly an obiectqof our invention to provide new organic bases. A furth r object .1 vtry-provide a process for preparing organic bases. Other objects will become apparent hereina-iter.

. :In accordance with -ourinvention. w prepa yano cyanine bases in condensing a heterocyclic nitrogen .base.,,containins .in'a reactive p tion a-cyancmethyl group, with -.a.cyolammoni1.1m

quaternary salt containing in a reactive position a member selected ,rrom the g oup onsisting p halogen atoms, 'thioether groups, psarylaminovinyl (including acylated p arylaminovinyl) groups, w.-arylamino lfi-butadienyl (including acylated w-arylamino-1,3-butadienyl) groups, a:- ,5 arylamino-1,3,-5-hexatrienyl (including acylated w-arylamino 1,3;5-hexatrienyl) groups. Advantageously the condensations are effected in the presence of a basic condensing agent. Tertiary organ c basic condensing agents are advantageously employed especially with cyclammonium quaternary salts containing a. halogen atom or a thioether group. Strong organic bases, i. e., th se having a dissociation constant substantial- 1y great r than that of p ridine, are advantaeously employed. When empl ing s ong organic bases. it is advantageous to effect the con- .d ns t s in a s v tsuc a an alcohol of th formula CnH2n+1OH wherein n representsa posi- ,tive integer f from one to three, for xamp Heat accelerates the condensation.

The following examples will serve to illustrate our new cyanine bases and the manner of obtainingthe same.

5 Example 1.--'2 [cyano(1 ethyl-4(1).-quinolyli- 2 dene) methyl] quinoline and its hydrochloride 7.86 g. (1 mol.) of 4-phenylmercaptoquinoline ethiodide, 3.36 g. ;(1 mol.) of 2-quinolylacetonitrile and 2.0 g. (1 mol.) of triethylamine'were placed in 25 cc. of absolute ethyl alcohol. The mixture was boiled, under reflux, for minutes. The orange reaction mixture was cooled and stirred with 150 cc. of a 4% aqueous solution of sodipm hydroxide. The aqueous liquors were .decanted iromthe stick-y brown precip ta The pr cipitate was "dissolved in 100 cc. of hot ethyl alcohol. The solution was filtered-while ho and the yanine base precipitated as its hydrochloride by adding tothe filtered solution, .10 cc. of an alcoholic solution of hydrogenchloride .-1.5 gram -10. hydr g ch oride p r Copp rs crystals .qf the base separated at once. The mixture was then diluted to .200 cc. with acetone. The acetone mixture was chilled and filtered. In this manner a 72% yield of the hydrochloride was obtained.

It was recrystallized from absolute ethyl alcohol 0 .c' pe -g a .of hydrochloride) and obtai ed, in 62% yield, as brilliant coopery -rred crystals m ting with decomposition at vl 8 to 169 Q- 1.0 3- (1 mo o the coppem ed cryst ls and 10.6 a .(1 1.+ 1oo% excess) of triethylamine were stirred together in cc. of absolute ethyl alcohol until solution was complete. The mixture was then poured into 300 cc. of water, whereupon the cyanine base precipitated. The base was filtered ofi by suction. Yield 0.8 g., 89%. The base was recrystallized from absolute ethyl alcohol and obtained as minute red crystals having a'green reflex and melting with decomposition at 151 to 152 C. Yield 0.6 g., 67%. The

base slightly sensitized a photographic silverl, halide emulsion. The hydrochloride of the base, on the other hand, didnot sensitize photographic silver halide emulsions. 'Thebase gave ajyelloworange solution in methyl alcohol, while ithe hydrochloride gave a bluish red'solution.

4-quinolylacetonitrile can be. prepared accord:

ing to the method of Borsche and Biitschli, de- J- scribed in Ann. 529, 271 (1937).

Example 2.2-[cyano-(3-ethyl-2(3) memorializolylidene) methyl] benzothiazole awe/rye I mean. l

6.4"(1 mol.) of 2-ethylmercaptobenzothiazole ethiodide, 3.5 g. (1 mol.) of 2-benzothiazolylace- 221 0.. Yield 4.7 g., 70%. The base gave a pale yellow solution in methyl alcohol. The basesen- 'sitizeda.gelatino silverwchloride emulsion slightly to'415mu; I

2-benzothiazolylacetonitrile can be prepared according to'th'e method described by Borsche and Doeller, Ann.'537 54 (1938).

Example 3.2- [1 -cyano'-3- (1 -ethyl-4 (1) -quinolylidene) propenyl] benzothiazole 1.0 g. (1 mol.) of 2-benzothiazolylacetonitrile,

2.55 g. (1 mol.) of 4-(p-acetanilidovinyl) -quino-,

line ethiodide and 0.6 g. (1 mol.) of triethylamine were placed in 25 cc. of absolute ethyl alcohol. The mixture was boiled, under reflux, for 5' minutes. -Green crystals of cyanine base separated immediately from the purplish reaction mixture.

7 The mixture was chilled, the base filtered off, the

basewashed with methyl alcohol and dried in the air. Yield of green crystals was 1.8 g'., 89%.

- After recrystallization from acetone (125 cc; per

gr'a m of base), the base was obtained as minute green crystals, melting with decomposition at Example 4. 2- [1-cyano-3-(3-ethyl-2(3) -benzoxazolylidene) m'openyll -quinolz'ne 1.7; g. (1 mol) of 2-quinolylacetonitrile, 4.34 g. (1 mol.) of 2-(p acetanilidovinyl) benzoxazole ethiodide and 1.0 g. (1 mol.) of triethylamine were jplaced in 15 cc. of absolute ethyl alcohol.

mixture, wasboiled, under reflux, for 10 minutes.

The

The orange mixture was chilled, the base filtered oil, the base washed with 'a small amount of absolute ethyl alcohol'and dried in the air. The a yield of orange crystals was 2.8 g., 82%. After recrystallization from acetone (165 cc. pergram of base),- the base was obtained as minute orange crystals. melting at 231 to 232 C. Yield 2.7 g.,

The base sensitized a photographic gelatino-silver-bromiodide emulsion'very weakly out to about560 mu., with some'desensitization in the blue region. The base gave a yellow solution in methyl alcohol.

Example 5.--z [1-cyano-3-(3-methyl 2(3) emazolinylidene) propenyl] qainoline r 1.7 g. (1 mol.) of 2-duinolylacetonitrile, 3.9 g.

(1' mol.) of 2 3 acetanilidovinyl) th'iazoline methiodidez'm'd1.0g. (1 mol.) of triethylamine were placed in 15 cc. of absolute ethyl alcohol. The mixture was boiled, under reflux, for 10 minutes. The orange reaction. mixture was chilled, the cyanine base was filtered oil, the cyanine base washed vwith absolute ethyl alcohol and dried in the air. Yieldof orange crystals was 2.9 g.,'99%. A fter' recrystallization from absolute eth'yl' alcohol (79 cc. per gram of base), the base was obtained, in yield, as brown needles having a metallic reflex and melting with decompo ition at 174 to 175=.C. The base sensitized a photographic gelatino silver bromiodide emulsion very weakly out to about 560 mu., with considerable desensitization in the blue region. The base gave a'yellow solution in methyl alcohol.

[ xam le 6.2-[1+cyano-3-(3-ethyl-26) memo thiazolylidene propenyll quinoline 7 1 'CN 6 6 9 20 (3)11 (2)H\(1J 1 7 2 s 4.5 g. (1 mol.) of Z-(p-acetanilidovinyl) -benzothiazole ethiodide and 1,7 g. (1 mol.) of 2-quin-" olylacetonitrile were placed in ,15 cc. of pyridine.

"The mixture was boiled, under reflux, for 3 min- 7 222150 223C. Yield 1.5 g 74%. The base sensitized a photographic gelatino-silver-bromiodide emulsion fairlystrongly between about 520 and about 080mm, with a maximum at about 635 mu. r The base gave a. blue solution in methyl alcohol.

utes. .The orange reaction mixture was cooled, diluted to C. with water and chilled to 0 C.

The aqueous liquors were decanted and the tarry residue was stirred with methyl alcohol until Q crystalline.

The crystalline cyanine' base was filtered ofi,washed with water, then with methyl alcohol, and then dried .in the air. 3.0 g., 85% yield, of a reddish brown powder were thus obtained. After recrystallization from methylalcohol (250 cc. Per gram of base), the base was obtained as red needles, having a green reflex and Example 7.--f2-'[1-cyano-5 1-ethyl-4'( 1) :quino- IZylidene) -.1,3-pentadienz/Zl -benzothiazole 1.74 g. (1 mol.) of 2-benzothiazolylacetonitrile, 4.7 g. (1 mol.) .of-4- (4-acetani1ido-1,3-butadienyl) quinoline ethiodide and 1.0g. (1 .mol.) of triethylamine were placedzin 50 cc. of absolute ethyl alcohol, The mixture was boiled, under reflux, for .5 minutes. The cyanine base separated at once from the boiling mixture. The reaction mixture was chilled,"the base filtered off, the base washed with methyl alcohol and driedin the air. Yield of dark green crystals was 3.0 g. This crude product was veryimpure. The desired base was obtained by extracting the crude product with 800 cc. of,acetone-andconcentrating the 800 cc. to 150 cc. and chilling to 0 C. In this manner 1.2 g., 32% yield, of green crystals were obtained. After recrystallization from acetone (125 cc. per gram of base), the base was obtained as green needles melting at 201 to 203 C. with decomposition. Yield 0.6 g., 16%. The base sensitized a photographic gelatino-silver-bromiodide emulsion strongly from about 680 mu. to about 780 mu. with amaximum at 740 mu. The base gave a blue solution in methylalcohol.

Example 8.-2-[1-cyano-5-(1-ethyZ-2(1) -quino- ZJlidene) -1,'3-pentadienyl] benzothiazole 1.74 g. (1 mol.) of 2-benzothiazolylacetonitrile, 4.7 g. (1 mol.) of 2-(4-acetanilido-1,3 butadienyl) quinoline ethiodide and 1.0 g. (1 mol.) of triethylamine were placed in 50 cc. of absolute ethyl alcohol. The mixture was boiled, under reflux, for 5 minutes. The cyanine base separated at once from the boiling mixture. The mixture was chilled, the base filtered oil, the base washed with methyl alcohol and dried in the air. Yield of green crystals 3.8 ,g.,,v 100%. After recrystallization from acetone (300 cc. per g. of base), the base was obtained, "in 58% yield, as green crystals melting at 230 to 233 C. with decomposition.

The base sensitized a photographic -gelatino- 740 mu. "with a maximum :at 640mm. :gave :a blue solution in methyl alcohol.

silver jbronnodide emulsion stron ly 30:11.58) to The Example .'9.-4-i[1-c11an0-5- i(3=ethyl=2(3) bcnznthiazalylidene)41,3-pentadieny1l gumoline 458 g. (1 mol.) of *2-(4-acetanilido) -1,3-butadienyl benzot-hiazole ethiodide, 1:7 'g. ('1mo'l;) of i-quino'lylacetonitrile and 1:0 g. "("1 mol.) of triethylamine were placed in 25 cc. of absolute ethyl alchol. The mixture .was boiled, under reflux, for 5 minutes- The red mixture was then cooled and diluted with cc. of water. The diluted vmixture was chilled to 0 C. and the aqueous liquors were decanted. The residual green car was stirred with '25 cc. of :hot acetone until completely crystalline, The acetone mixture was chilled, the crystalline eyanine base filtered oif and washed with acetone. Yield 1.9 g., 50%. After recrystallization from acetone cc. per gram of base), the cyanine .base was obtained as .steel blue needles, :melting "with decomposition at to 187 C. .The :base sensitized a photographic ,gelatinmsilvnbmmiodide emulsion feebly out to .670 :mu.

Example "1'0.;2-'[1-cyano-7-(3-ethyl-2'(3) -benzothiazo'lylidene) 1.3.5 -heptatrienyll :benzothi- .azole 1.74 g. (1-mol.) of '2 benzothiazolylacetonitrile, 5.0 g. (1 mol.) of 2-[6-acetanilido (1,3,5-hexatrieny1) benzothiazole ethiodide. and 1.0 g. (1 mol.) of triethylamine were placed in ,25 cc. of absolute ethyl alcohol. The mixture was boiled, "under reflux, for 5 minutes. The cyanine base separated at once from the boiling mixture. The mixture was chilled, the base filtered ofi, washed with methyl alcohol and dried in the air. Yield of copper bronze crystals was 3.3 g. This crude product was very impure. The base was obtained by extracting the crude product with 900 cc. of acetone, concentrating the acetone extract 170.25 cc. and chilling to 0 C. .In thi manner 1.0 g., 24% yield, of green crystals was obtained. After recrystallization from acetone (140 cc. per gram of base), the base was obtained as .minute blue crystals melting with decomposition at 193 to 195 0. Yield 07 g.,, 17%... This base sensitizedarihotographic gelatincesilver bromiodide strongly .from .600 to 820 mu. with amaximum at 760 mu. The base gave a blue solutioninmethyl alcohol.

Example '11.--4-,[1'-Cy(Z7L0-13-f(1-wethyl-e4 c1.) equinolylidene) zaropenyllquinvliue emulsion mixture was biled,under reflux, for minutes. The red mixture was cooled, diluted with 75 cc. of

water, and the diluted mixture chilledto 0 C.

The tar remaining after decanting the aqueous liquors, was stirred with 25 cc. of hot acetone until crystalline. The acetone mixture was chilled, the V crystalline base filtered ofi and'washed with ace- Yield 3 g., 86%. After recrystallization from methyl alcohol (115 cc. per gram of base),

7 the base was obtained, in 67% yield, as green slightly. mapl 12.--2-[1-cyano-3-(3-ethyl-28) -benzothiazolylidene) p'r penyll -benzoth z'azole v9.0 g. (1 mol.) of Z-(s-acetanilidovinyl) -benzothiazole ethiodide, 3.5 g. (1 mol.) of 2-benzothiazolylacetonit'rile and 2.0g. (1 mol.) of triethylamine were placed in 100 cc. of absolute ethyl alcohol- The mixture was boiled, under reflux, for minutes. Blue crystals of base separated at once from the boiling mixture. The mixture was chilled, the base filtered off, washed with methyl alcohol and dried in the air. Yield 6.4 g., 89%.

After crystallization from acetone (100 cc. per gram of -base), the base was obtained as red needles, having a silver reflex, and melting at 210 to 212 C. with decomposition. Yield 4.8 g., 67%. The base gave a pink solution in methyl alcohol. The base sensitized a gelatino-silver-bromiodide emulsionout to 600 mu. with a maximum at'550 mu. v e

. thiazolylidene) -1,3-pentadienyll -benzothz'azole J 10.4 g. (1 mol.) of Z-(FL-aCGtaniIidO-I,3-butadienyl) -benzothiazole etho-p toluene-sulfonate; 3.5 g. (1 mol.)' of 2-benzothiazolylacetonitrile and 2.0

. g.(1 mol.) of triethylamine were placed in 100 cc. of absolute ethyl alcohol. The mixture was boiled,

under reflux, for 15 minutes, Blue crystals of the base separated at once from the boiling solution. The mixture was chilled, the base filtered off,

. Washed with methyl alcohol and dried in the air.

The crude product was boiled with 200 cc. of methyl alcohol, filtered from the hot methyl alcohol and dried in the air. Yield of blue crystals Example 14.--:z [1,- came- 5-(1-ethyl -2(1;)-pnaphthothiazolylz'dene) -1,3-pentadienyll -.'benzoth'iazole 15.3 g. (1 mol.) of 2- (4-acetanilido-1,3buta ,dienyl)-,8-naphthothiazole ethiodide, 1.74 g. (1 mol.) of 2-benzothiazolylacetonitrile and 1.0 g. (1 mol.) of triethylamine were placed in 100 cc. of absolute ethyl alcohol. The mixture was boiled, under reflux, for 15 minutes. The base separated at once from the boiling mixture. The mixture was chilled, the base filtered ofi,.washed with methyl alcohol and dried in the air. Yield of darkcrystals 3.5 g., 80%. After crystallization from pyridine (95 cc. per gramof base), the 7 base was obtained as dull blue crystals melting with decomposition at 240 to 242 C. Yield 2.1 g., 48%. The base gave a blue solution in methyl alcohol and sensitized a gelatino-silverbromiodide emulsion fairly strongly between about 560 mu. and 710 mu. with a maximum at 670 mu. 7 a

In a similar manner 2-(B-aoetanilidovinyD-3- phenylbenzothiazolium iodide can be condensed with 2-benzothiazolylacetonitrile to give 2-[1- cyano 3 (3phenyl 2(3)-benzothiazolylidene) propenyll benzothiazole. 2(,8-acetanilidovinyl)-'- 3-phenylbenzothiazolium iodide is described in the copending application of Leslie G..S. Brooker and William W. Williams, Serial No. 353,500, filed August 21, 1940 (now United States Patent 2,330,203, dated September 28, 1943). p

In accordance with our invention dialkylaminostyryl and dialkylaminocinnamyl bases can be prepared by condensing dialkylaminobenzaldehydes or dialkylaminocinnamic aldehydes with heterocyclic nitrogen bases containing, in a reactive position, a cyanomethyl group. These condensations are advantageously effected in the presence of a water-binding agent, e. g., a waterbinding agent comprising an anhydride of a monocarboxylic organic fatty acid. Alternatively these condensations are advantageously effected in the presence of a catalyst comprising essentially a strong secondary organic. base, such as piperidine. When employing such a catalyst, the condensations are advantageouslyjelfected in a solvent, such as an alcohol of the formula CnH2n+1OH wherein n represents a positive integer of from one to three. Heat accelerates the condensations. I

The following examples will serve to illustrate our new cyano dialkylaminostyryl and cyano dialkylaminocinnamyl bases and. the manner of obtaining the same.

Example 15. '4- [1 -cyano (p-dimethylamino) styryl] quinoline 1.7 g -(1 mol.) of4-qulnolylacetonitrile and 3 g. (1 mol.'+100%' excess) of p-dimethylaminobenzaldehyde were placed in 15 cc. of acetic anasaswas hydride. The-.mixture was boiled, under-reflux, for one hour. The brownish mixture waschilled to C. when greenish yellow crystals of styryl base separated. These were filtered off and recrystallized from methyl alcohol (43 cc. per gram of .base). "The base wasthusxibtained, in 47% yield; as yellow flakes melting at 153 to 154 C. The base sensitized a gelatino-silver-bromiodide emulsion weakly out to 540 mu.

-Ea:a,mp1e .'1-6. -.2- [.1 -cyaho-4 (p dimet-hi lamirio) 1,;3-butadienyll be-nzothiazoie 1.5 g. .(1 mol.) of 2-.benzothiazolylacetoni rile, 1.5 g. (.1 mol.-) of, p d-imethylaminocinnamalde hyde and, drops 'of e'piper-idine were placed in cc.-of absolute ethyl alcohol. The mixture was boiled, under reflux, for lfliminutes Thecinnamyl basezseparated at --once .irom the boiling mixture, The orange .mixture was--chilled, the base filtered off, washed with methyl alcohol and dried in the air. Yield of minute dark crystals 2.3 g.,..81%. After recrystallization dram acetone (225 7 cc. per ,gram of base), the base was -ob tained, .in 53% yield, as minute purple crystals, melting with decomposition at 226- :to "228 The base sensitized aphotographicgelatihmsilver-bromiodide emulsion very weakly; out $01640 mu., with considerable desensitization in the blue region. The base gave orange solution in methyl alcohol."

Any of the cyano cyanine bases, cyano istyryl bases or cyano cinnamyl bases of .our invention can be converted into the corresponding dyes by quaternarization with alkyl salts. The following examples will serve to illustrate the manner of obtaining-.suchdyes.

Example 1?.- 1:a-b ano-sethyl-herethylthia-Q. 'carbocyanine bromide benzothiazolylidene)propenyllquinoline rand 13.4

g. 1 mol.+ 1 00 of .methylep toluenesulfonate were heated together. at 125'-:to130'\C..:ior-about The green solid mass was :cobledand recrystallization from methyl alcohol (20.00. per;

gram of dye) the dye was obtained as purple crystals with a bronze reflex and melting'with decomposition at 262 to 263 C. The dye gave a bluish red solution in methyl alcohol. Yield 0.25 g.,' 55% The-dye'sens'itizeda gelatino-silver-' bromiodide emulsion 1 weekly :out to 650 rmmwvith amaximum at 62011111. I

1;2:g.--'(1 molt) or 2 l-cyano 3- ta-ethyl 2 t3h benzothiazolylidene) propenyll benzothiazole and 1:5 g.-"( 1 rnol.-+-200%' excessi oi diethyl suliaite were heated together "for 9 h0urs one 'steam belth. After coolingmthe mixture was'washedby tation with several BO cc. portions o f absolute diethyl ether. The was'heiim-i-xture was themdissolved "in '30 =-cc. -of hot "methyl alcohol; "To t'he hotrnethyl alcoholic=56lution-was added-an excess of sodium iodide in methyl alcoholic solution. The dye iodide precipitated. "Thedyewasililtered off, "washed water, then'wi th acetone and dried in ithe air. Yield of red crystals- 1. 1 g.. 65% After recrystallization from methyl alcohol- 830 cc. per gram of dye) the dye was obtainedqas steel :blue crystals-melting with decomposition-at 219 to 222 C. Yield 0.9 g., 53%. The dye -g'ave a red solution in methyl alcohol. The dye sensitized 1a .'gelatino silyer bromiodide emulsion out to 600 mu. '-with:,a maximumzat 550 mu.

Our new cyano bases can be represented by the following general formulas:

I represents a methine "groupfR; represents an "orgame radical eelected from the "group consisting of alkyl an-dary-l "groups, R. and R"- each-'repre sent-ana1kyl jgroup and'Q and Z-eaeh represent the non-metallic atoms "necessary to "complete a heterocyclic nucleus. p In accordance with ;our invention, the cyano cyanine bases, cyano styryl bases or cyanocinnamyl bases are hydrolyzed to the corresponding unsubstituted bases. During the hydrolysis, :the

cyano group is-convertedi-lto a .carboxyl group which loses carbon dioxide. The hydrolysis is advantageously effected with anacid hydrolysis catalyst. Mineral acidstare advantageously employed as acid hydrolysis catalysts. Heat accelerates the hy'clrolysis.

The following examples will serve to illustrate the manner of obtaining unsubstituted bases from the .eyano bases. a

tin?

azolyliden'e )propenyllquinolme waszrplaced 111.150

'. of 60% sulfuricacid. The mixture was'heatd to boiling, under reflux. 1 A vigorous evolution of carbon dioxide occurred at the boiling point. The mixture 'was boiled; until 'the evolution of carbon dioxide ceased (about 5.minutes). The mixture was then poured onto ice and made 211-- kaline with ammonium hydroxide. The orange precipitate was filtered oil, washed with water and dried. In this manner 0.9 g.,'9'7% yield, of greenish solid was obtained. After recrystallizationfromabsolute ethyl alcohol (1'7 100. per gramoibase) the base was obtained as abrown powder, melting .with decomposition at 126 to 1.27? .C.;Yield, 0.65 g.-, 70%.; 'The base sensitized a photographic gelatino-silver bromiodide emulmm weakly outto 640 mu. j

Ina similar manner, 4- [e-(a-eth i-m) -benzo thiazolylidenelpropenyl]quinoline was prepared from 4-' [1-cyano-3-(3-ethyl- 2 (3l-benzothiazolyl- V idene) propenyl]quinoline. The base was, ob-

tained after recrystallization from, ethyl alcohol (140 copper. gram-oi base) as glistening orange needles, melting withdecompositionv at 195 to 196? C. The base sensitized a photographic gelatino-silver-bromiodide emulsion weakly out Example 20.4-[5-'(3-e thyl-2(3)-benzothiazolylidene) -1,3 -p'entad1em/Z]quinoline hated with considerable insoluble colorless mate- Example 22.-"2 t5 (s ether-"2(3) be1i.othz'a-" f "zolylideyim 51,3-pentad ienyll -quinoline 4.2 g. of 2-i -cyano-5-(3-ethy1-2(3) -benzothiazolylidene) -1,3-pentadienyl] quinoline were placed in 150 cc.'of 60%-sulfuric acid. The mixture' was boiled, under reflux, for Sminutes. The mixture was cooled, poured onto ice, and made alkaline with ammonium hydroxide. The crude cyanine base was filtered oii. It was contamirial; The crude product was extracted withlOD cc. of absolute ethyl alcohol. Upon chilling the alcoholic extract red crystals of cyanine base separated. These were filtered oifand recrystallized from absolute ethyl alcohol (65 cc. per gram of base) and obtained as minute red crystals melting at 142 to 144 C. with decomposition. Yield 1.2 g., 31%. The base sensitized a photographic gelatino-silver-bromiodide emulsion fairlyflstronglybetween about 560 mu. and760 mu.' with a maximumat about 710 mu.

7 In a similar "manner, 2+[5- (1-ethyl-'2(1)- quinolylidene) 1,3- pentadienyll benzothiazole wasiobtained as a dull-black powder melting with and obtained, in 36% yield, as a dullredpowder,

melting with decompositionat 1:37 "t 1395 0.} The base had r -sensitizing action on photographic silver halide emulsions. j

ramble .21. 2-u1-eui zf- 4(1) tummy/11am) V V r I methyll-quinolz'ne W I 2 g. or 2-[cyano-(1-ethyl-4(1) -quinolylidene) methyl] quinoline'hydrochloride were placed in 75 cc. of 60% sulfuric acid. The mixture was 7 tion on photographic silver'halide emulsions.

decomposition at 153" to 155 0., from 241- cyano-5-(1-ethyl- -quinolylidene)".-' 1,3 pentadienyllbenzothiazole,

ma a; 231-2- 14 -Y t -dimem'yz mm nenyzi 1,3-butadien1ll] benzothz'azole v 11 a "4k 7 2ccH.='cH-.c11 ='on 2.0 g. phenyD-LB-butadienyll benzothiazole and 150 cc.' of 60% sulfuric acid-were mixed togetherr melting with decomposition at 1773" t0'175'C..

Its methyl alcoholic, solution was,-yellow. It

sensitizedaiphotographic "silver halide emulsion very. slightly.

ragtime "24:2 [7;- s ethyl-=28)fbenzothiazolyl idene) -1,3,5-heptairiem/Z lbenebthiazole 1.0 g. for;2-l1-cyano-7 (3-ethyl-2(3) benzothiazolylidene') 1,3,5? heptatrienyl] benzothiazol'e'and "cc..of 60% 'sulfuric'acid were mixed together. The mixture wasiboiled', under-refiux,r:

of 2- l-cyano-4 ip-dimethylamino- 1 Yield of green crystals The base was recrystallized I mass ng.

until evolution of carbon dioxide ceased (about Iected frcmsthe onsisting'of alkyl aud'ai'yl" 3. minutes) The mixture was cooled. rapidly and poured onto a mixture of crushed ice and watercontaining ammonium hydroxide in excesscof that required to neutralize the sulfuric acid. The

base precipitated. It was filtered off, washed with water and dried in the air. Yield .4 g., 43%. After recrystallization from acetone (800 cc.

per gram of base), the base was obtained as dull black crystals, melting with decomposition at 141 to 142 C. Yield'0.3 g., 32%. Solution in methyl alcohol was red. Gave no sensitizing action on aphotographic silver halide emulsion.

In the preparation of photographic emulsions sensitized with the herein described bases, it is only. necessary to disperse the bases-in the emulsions; It is convenient to add the bases to the emulsions from solutions in appropriate solvents.

Acetone and methyl alcohol have proven satis factory as solvents for this purpose. Sensitization by means of these bases is, of course, primarily directed to the ordinarily employed gelatino-silver-halide developing-out emulsions. The bases are ordinarily incorporated in the washed,-

finished emulsions and should, of course, be uniformly distributed throughout the emulsion. The concentration of the bases in the emulsions can vary widely,- i. e., from about to about 100 mg. per liter of flowable emulsions. The concentration of the base will vary according to the type of light-sensitive material in theemulsion and 9.0-- cording to the effect desired. The suitable and most economical concentration for any given emulsion will be apparent to those skilled in the art upon making the ordinary tests and observations customarily employed in the art of emulsion making. To prepare a gelatino-silver-halide emulsion sensitizing with one of these bases, the following procedure is satisfactory. A quantity of the base is dissolved in acetone or other suitable solvent, and a volume of this solution (it may be diluted with water) containing from 5 to 100 mg. of base is slowly added to about 1000 cc. of gelatino-silver-halide emulsion, with stirring. Stirring is continued until the base is uniformly distributed throughout the emulsion. With most of these sensitizing bases, to 20 mg. of base per liter of emulsion suffices to produce the maximum sensitizing effect with the ordinary gelatinosilver-bromide (including bromiodide) emulsions. With gelatino-silver-chloride emulsions somewhat larger concentrations are required to produce the optimum sensitizing effect. The above statements are only illustrative and are not to be understood as limiting our invention, as it will be apparent that these bases can be incorporated by other methods in the photographic silver halide emulsions customarily employed in the art. For instance, the bases may be incorporated by bathing a plate or film upon which an emulsion has been coated in a solution of the base in an appropriate solvent. Bathing methods, however, are not to be preferred ordinarily.

What we claim as our invention and desire to be secured by Letters Patent of the United States 1. An organic base selected from the group characterized by the following general formula:

. Q 0N --z------;

wherein d and e each represent a positive integer of from 1 to 2, n represents a positive integer of from 1 to 4, R represents an organic radical segroups. and Q and Z eachrepresenththe non; metallic atoms necessary to complete a heterocyclic organic nucleus containing from 5 to 6 atoms the heterocyclic ring.

2. An organic base selected from the group characterized by the following general formula:

CN 5 --Z- 25 wherein n represents a positive integer of from 1 to 4, R represents an alkyl group, Q represents the non-metallic atoms necessary to complete a henzothiazole nucleus, and Z represents the nonmetallic atoms necessary to complete a quinoline nucleus.

4. A 2 [1-cyano-3-(l-alkyl 4(1): quinolylidene) propenyll'benzothiazole having thefollow ingformula:

wherein R represents an alkyl group.

5. 2-[1-cyano-3-(1-ethyl-4u) quinolylidene) propenyl] benzothl azole having the following formula:

'6. An organic base. selected from the group characterized by the following general formula:

wherein n represents a positive integer of from 1 to 4, R represents an alkyl group, Q represents the non-metallic atoms necessary to complete a heterocyclic organic nucleus containing from 5 to 6 atoms in the heterocyclic ring and Z represents the non-metallic atoms necessary to complete a benzothiazole nucleus.

7. A 2-[1-cyano-5- (3-alky1 -2(3) benzothiazolylidene) -l,3-pentadienyl] -benzothiazole having the following formula:

wherein R represents an alkyl group.

8. 2-[1-cyano-5-(3-ethyl-2(3) benzothiazoh y1idene)-1,3-'pentadieny1] benzothiazole having the followingformuiaz' 'i i CN'V 9. Aiz-u cyano-7-(3-a1ky1-2 (3) -ibenzothiazolylidene) 1,3,5 -1 heptatrienyl] benzothiazole having the followingformula: I

wherein R represents an alkyl group; A

10. 2-[1-cyano-7-(3-ethy1 2(3) benzothiazolylidene) 1,3,5 heptatrienyl] benzothiazole having the following formula: 1 a a.

11. A 'process'for preparing an organic base comprising condensing a heterocyclic nitrogen base containing, in'a reactive position, a cyan'-: 'omethyl group, with a cyclammonium quaternary salt selected from the group consisting of Cyclammonium quaternary salts containing from 5 to 6 5 leoted from the group consisting of cyclam-' monium quaternary salts containing from 5 to 6 atoms in the heterocyclic ring and containing in a reactive position, a member selected from the group consisting of halogen atoms, thioether groups, fi arylamino-vinyl groups, w-arylamino- 1,3 butadienyl groups and w-arylamino 1,3,5- hexatrienyl groups. w

13. A process for preparing an organic base comprising condensing, inthe presence of a tertiary organic base condensing agent, a hetero-V cyclic nitrogen base containing in a reactive posi-: tion a cyanomethyl group, with a cyclammonium quaternary salt selected from the group consisting of cyclammonium quaternary salts containing 7 from '5 to 6 atoms in th heterocyclic ring and containing in a reactive position, a member'selected from the group consisting of halogen atoms, thioether groups, fi-arylaminovinyl groups, to-

'ary1amino-1,3-butadieny1 groups and wary1aminc-1,3,5-hexatrieny1 groups.

LESLIE G. s. BROOKER.

, v ROBERT H. SPRAGUE. 

